Who's the world's wealthiest — today?

Fortunes can be fickle things. To keep on top of the 1%, Bloomberg today launched an index that ranks the world’s wealthiest people every day. No. 1 today, Mexico's Carlos Slim, but who knows what tomorrow will bring

Carlos Slim, the telecommunications tycoon who controls Mexico’s America Movil SAB, is the richest person on Earth, according to the Bloomberg Billionaires Index, a daily ranking of the world’s 20 wealthiest individuals.

The 72-year-old’s net worth fell US$478.4 million in a day to US$68.5 billion as of the close of markets on March 2, as U.S. moguls Bill Gates and Warren Buffett placed second and third on the list compiled by Bloomberg News. Brazil’s Eike Batista, who ranks 10th, still covets the top spot after vowing a year ago that he’d become the world’s wealthiest man by 2015.

“I’m competitive,” Batista, who trails Slim by almost US$39 billion, said in a March 2 telephone interview from Rio de Janeiro. “It’s Brazil’s time to be No. 1. Brazilians have always admired the American dream. What’s happening in Brazil is the Brazilian dream and I happen to be the example.”

The Bloomberg Billionaires Index takes measure of the world’s wealthiest people based on market and economic changes and Bloomberg News reporting. Each net worth figure is updated every business day at 5:30 p.m. in New York. The valuations are listed in U.S. dollars.

Today’s ranking was published with the release of new billionaires profile pages in the Bloomberg Professional service. The profiles feature a transparent analysis of how each billionaire’s fortune was calculated.

Canadian David Thomson, chairman of Thomson Reuters, made the top 20, coming in at 19th richest with his $22.7-billion fortune.

Slim’s fortune has increased 11% this year, according to the index. A spokesman for Slim didn’t immediately return a telephone request for comment.

Gates, Buffett

Gates, 56, co-founder of Microsoft Corp. in Redmond, Washington, is worth US$62.4 billion, down US$102.1 million on March 2 and up 11% year to date.

The fortune of Buffett, 81, chairman of Omaha, Nebraska- based Berkshire Hathaway Inc., declined US$336.9 million to US$43.8 billion on March 2 and is up 2.4% in 2012. Almost all of Buffett’s wealth is held in Berkshire Hathaway, the publicly traded holding company he has run since 1965.

The combined net worth of the 20 richest people is US$676.8 billion. Nine are Americans, including three from the family of Sam Walton, the founder of Wal-Mart Stores Inc.

Number seven is Larry Ellison, 67, chief executive officer of Redwood City, California-based Oracle Corp., the world’s third-largest software maker after Microsoft and SAP AG. His US$38 billion fortune puts him US$4 billion ahead of brothers Charles and David Koch, who each own 42% of Koch Industries Inc., one of the biggest closely held companies in the world by revenue. Charles, 76, and David, 71, control the Wichita, Kansas, refiner and chemical maker.

Batista, 55, whose investments range from iron ore to coal, is worth US$29.8 billion, up US$133.9 million on March 2. His fortune has grown 32% this year, the most on the list.

The House Wins

Sheldon Adelson, the casino magnate who owns 47% of Las Vegas Sands Corp., which operates resorts in Macau and Las Vegas, is number 13 with US$25.7 billion. Adelson, 78, and his family have pledged at least US$10 million to a super-PAC supporting Newt Gingrich, a Republican presidential candidate.

Liliane Bettencourt, 89, who with her family owns 31% of Paris-based cosmetics company L’Oreal SA, is last on the ranking. Bettencourt was the subject of an international scandal in 2007 when her daughter, Francoise Bettencourt Meyers, filed a lawsuit accusing a family friend, photographer Francois- Marie Banier, of exploiting her mother’s frail state. Evidence later revealed Bettencourt had granted more than US$1 billion in cash and gifts to Banier. In October, Meyers and two grandsons became guardians of the clan’s US$22.4 billion fortune.

Diluting Zuckerberg

Mark Zuckerberg, the 27-year-old founder of Facebook Inc., the world’s largest social-networking company, didn’t make the cut. Based on a roughly US$100 billion valuation the Menlo Park, California-based company has been trading at in the private market, Zuckerberg’s stake may be worth US$21 billion, or about 25% less than previous estimates, once Facebook holds its initial public offering.

The reason: Facebook will issue more than 500 million shares of its Class B stock at the offering, diluting Zuckerberg’s ownership to 21% after he exercises 120 million options and sells about 42 million shares to cover the tax bill associated with the gain from those options.

Sweden’s Ingvar Kamprad is the richest European, according to the index, ranking fourth globally with a US$42.5 billion net worth. Kamprad, 85, controls Ikea Group, the world’s largest furniture retailer, through a series of trusts and foundations he asserts he doesn’t own.

Luxury Goods

Bernard Arnault, the chairman of LVMH Moet Hennessy Louis Vuitton SA, places fifth. The majority of Arnault’s US$42.3 billion comes from his stake in Paris-based LVMH, the world’s largest maker of luxury goods. Arnault, 63, controls about 46% of LVMH’s outstanding stock through his family group, according to the company’s latest annual report.

Amancio Ortega, whose publicly traded Inditex SA owns the Zara clothing chain, is Spain’s wealthiest individual and sixth in the world with a US$38.8 billion fortune. Ortega, 75, has invested dividends from Arteixo-based Inditex into a real estate portfolio that owns office and retail properties in the U.S. and Europe.

No Russians appear in the index as falling metals prices hurt the fortunes of many of the richest oligarchs. Alisher Usmanov, 58, the Muscovite who controls the Metalloinvest metals and mining company and Digital Sky Technologies, which currently owns 5.5% of Facebook, is Russia’s wealthiest person thanks to a US$20.1 billion fortune.

Asia’s Wealthiest

Mukesh Ambani, 54, leads Asians with a net worth of US$26.8 billion, down US$185.4 million in a day. His fortune is up 25% this year, according to the Bloomberg Billionaires Index, as his shares in India’s top company by market value, Mumbai-based Reliance Industries Ltd., have risen 17%.

Lakshmi Mittal, the India-born chairman of ArcelorMittal, the world’s biggest steelmaker, is the third-richest Asian, with holdings valued at US$23.6 billion. In addition to his ArcelorMittal stake, the 61-year-old London resident owns hundreds of millions of dollars in U.K. real estate.

On the rise: Gina Rinehart, the Australian mining heiress who is worth US$20.4 billion. Rinehart, 58, the daughter of the man who discovered the mines that made Australia the world’s biggest iron ore exporter, inherited perpetual royalty rights to some of Rio Tinto Ltd.’s Hamersley mines in addition to other thermal and iron-ore deposits throughout the country.

Soaring demand for coal and iron ore from China have made Rinehart’s assets attractive to acquisitive industrial companies. In separate deals in the past year, steelmakers Posco and GVK Power & Infrastructure Ltd. agreed to pay a combined US$2.9 billion for pieces of Rinehart’s empire.